Diseases of the Echinacea Purpurea

Aster Yellows

• Aster yellows is a bacterial disease that mainly affects plants within the aster family, such as echinacea, sunflowers and marigolds. It is characterized by stunted growth and discoloration in the foliage and flowers, with the leaves taking on a veiny appearance and the flowers exhibiting an unusual greenish tint. Echinacea purpurea plants with aster yellows must immediately be removed and destroyed since there is no chemical treatment for the disease. However, aster yellows infections can be prevented by spraying insecticidal soap on the plants to repel leafhoppers, which host the bacteria and spread the disease.

Stem Rot

• Stem rot is an umbrella term for several types of fungal diseases known to afflict Echinacea purpurea plants. The most common culprits behind stem rot are Rhizoctonia solani and Sclerotium rolfsii, which are two strains of fungi that live in moist, organically rich soil. Echinacea purpurea plants afflicted with stem rot develop soft, weeping spots on the undersides of their leaves, as well as blackish stems that exude a somewhat foul-smelling liquid. Although no treatment is available for stem rot, it can be prevented by planting the Echinacea purpurea plants in a bed with excellent drainage and adequate spacing between each plant. Once the plants develop stem rot, they must be immediately removed and destroyed to keep from infecting the surrounding vegetation.

Wilting Diseases

• Verticillium, fusarium and pythium are three diseases collectively referred to as wilt. True to its name, the main symptom of wilt is damaged, dying leaves that drop off in large quantities as the disease progresses. More advanced cases of wilt cause the stems to retain water, which eventually leaks through the tissue and causes a bloated, saggy appearance around the base of the stems. Echinacea purpurea plants infected with wilt can be saved if the infection is caught early and treated with selective pruning of damaged stems and the application of nitrogen-rich fertilizer to bolster the plant's immune system. Advanced cases of wilt require the plant be removed and destroyed to avoid spreading the fungus to nearby plants.

Anthracnose Leaf Blight

• Anthracnose leaf blight is easily prevented by spacing Echinacea purpurea plants far enough apart to provide adequate air circulation among the leaves. Crowded plants are more likely to develop the disease, which is characterized by blackish lesions and curling on the young, newly formed leaves. Thin out Echinacea purpurea plants at the first sign of anthracnose leaf blight, creating at least 4 inches of space between each one. Failure to catch the disease in a timely fashion and prevent its advancement will eventually lead to complete defoliation of the plants and eventually death.